Effect of 1 mmol/L amino acids on (a) KYNA production and (b) tissue KYN concentration in tissue slices from the cerebral cortex. Experiments were performed as described in the text using 2 μmol/L KYN. KYNA and KYN were measured in incubation medium and tissue slice suspension, respectively. Values are expressed as mean ± SE (n = 3–7). *p < 0.05 versus control (Ctrl), determined by one-way analysis of variance with Dunnett’s multiple comparisons test.